Method of making an electric field device

ABSTRACT

An electric field device is obtained by the steps of employing a highly pure and mechanically electrically chemically and thermally extremely durable ceramic material, such as a high purity alumina porcelain, as a dielectric material, disposing electrodes on the shaped material before sintering by a thick film printing technique, such as screen printing, with a dispersion ink of finely divided metal, e.g. tungsten, and sintering the shaped material integrally with the electrodes. The product is extremely dense, mechanically electrically chemically and thermally durable and highly reliable.

This is a division of application Ser. No. 528,854, filed Sept. 2, 1983.

The present invention relates to various types of electric field devicesemploying fine ceramic dielectrics and a method for making the devicesas well as an electrostatic treatment apparatus of object matters makinguse of the electric field device.

Devices in which electrodes are provided on a surface of or within adielectric body, a D.C. high voltage or an A.C. high voltage (includinga sinusoidal wave, a rectangular wave, and a pulse-shaped high voltage)are applied between these electrodes to produce phenomena inherent to anelectric field such as gaseous discharge or electro-mechanicalphenomena, have been in themselves well known, and these phenomena areutilized as an ion source for charging or discharging of object mattersor utilized for electro-mechanical operations such as adhesion,repulsion or transportation of object matters caused by an electricforce (hereinafter generally called "electric field device").

Examples of the electric field devices serving as an ion source, havebeen disclosed in Japanese patent or copending Japanese patentapplications entitled at the old time "DENKITEKI GASU SEISEI SOCHI(Electric Gas Refining Device)" (Japanese Pat. No. 99242), and recently"SEIDEN FUNTAI TOCHAKU SOCHI (Electrostatic Powder Painting Device)"(Japanese Patent Application No. 51-103328), "RYUSHI KADEN SOCHI(Particle Charging Device)" (Japanese Patent Application No. 52-106400),"JODEN SOCHI (Charge Removing Device)" (Japanese Patent Application No.52-145838), and "KANRO SHIKI JODEN SOCHI (Pipeline Type Charge RemovingDevice)" (Japanese Patent Application No. 56-155419). In addition,examples of the electric field devices for utilizing forelectro-mechanical operations, have been disclosed in Japanese patentsor copending Japanese patent applications entitled "SESSHOKU GATA DENKAIKATEN SOCHI (Contact Type Electric Field Curtain Device)" (Japanese Pat.No. 983218), "SESSHOKU GATA DENKAI KATEN O MOCHIITA RYUSHI YUSO-KYOKYUSOCHI (Particle Transportation-Supply Device Making Use OF A ContactType Electric Field Curtain)" (Japanese Pat. No. 973106), "SESSHOKU GATADENKAI KATEN O MOCHITE RYUSHI O TOCHAKUSURU HOHO NARABINI SONO SOCHI(Method For Depositing Particles By Making Use Of A Contact TypeElectric Field Curtain And Apparatus For Practicing the Method)"(Japanese Pat. No. 1009331), "SESSHOKU GATA DENKAI KATEN O KOSEISURUHOHO OYOBI KORE O RIYO SHITA SESSHOKU GATA DENKAI KATEN SOCHI (MethodFor Constructing A Contact Type Electric Field Curtain And A ContactType Electric Field Curtain Device Making Use Of The Method)" (JapanesePat. No. 981125), "SESSHOKU GATA DENKAI KATEN O MOCHIITA SEIDEN FUNTAITOCHAKU YO BUSU (Electrostatic Powder Painting Booth Making Use Of AContact Type Electric Field Curtain)" (Japanese Pat. No. 1047574),"TAIDEN RYUSHI HASSEI SOCHI (Charged Particle Producing Device)"(Japanese Pat. No. 1048666), "SAISEN GATA DENKAI SOCHI (Thin Wire TypeElectric Field Device)" (Japanese Patent Publication No. 57-6385),"TANKYOKU DENKAI KATEN SOCHI (Monopolar Electric Field Curtain Device)"(Japanese Patent Publication No. 57-9856), "DENKAI KATEN SOCHI KARA NARUKABE (Wall Consisting Of Electric Field Curtain Devices)" (JapanesePatent Publication No. 57-24181), "ANZEN GATA DENKAI KATEN SOCHI (SafetyType Electric Field Curtain Device)" (Laid-Open Japanese PatentSpecification No. 52-108574), and "ISSO ROSHUTSU GATA SESSHOKU GATADENKAI KATEN SOCHI (One-Phase-Exposed Type AND Contact Type ElectricField Curtain Device)" (Japanese Patent Application No. 57-081779).

However, in common to all these electric field devices, a D.C. or A.C.electric field having an extremely high value is applied to a dielectricbody on the surface of which an electrode is supported or within whichan electrode is embedded and held, and especially concentration of theelectric field in the proximity of the electrode is remarkable. As aresult, in this concentrated electric field portion is generated localpartial discharge, not only as a matter of course when the portion isexposed in the air but also even in the case where the portion isembedded within the dielectric body, and hence the dielectric materialin this portion is subjected to bombardment by ions and electrons. Inthe case of employing the electric field device as an ion source, thisaction would naturally generate gaseous discharge on the electrode, andso, the action would become more and more remarkable. Also, if an A.C.voltage is applied to the electrode, the above-mentioned partialdischarge becomes especially remarkable. However, in the electric fielddevice in the prior art, because of ease in manufacture, in almost everycase synthetic resin or shaped inorganic insulator bonded by syntheticresin was used as a dielectric. In such a case the organic dielectricmaterial such as synthetic resin or the like was locally deteriorated bythe ion bombardment or electron bombardment caused by theabove-described partial discharge, especially when an A.C. high voltagewas applied, the deterioration proceeded quickly in a tree shaperesulting in growth of insulation defects called "treeing", andeventually it was enevitable that breakdown between the electrodesapplied with a high voltage would be generated within a relatively shortperiod of time. When inorganic insulator such as mica, ceramics, etc. isused in order to prevent such breakdown, although a life can be somewhatprolonged, not only it becomes difficult to perfectly embed an electrodewithin the insulator, but also as the structure of the insulator is notdense, when an interval or a thickness of an insulator portion is madethin for the purpose of enhancing an electric field effect, likewisebreakdown would arise momentarily at a low voltage, and therefore, itwas impossible to construct an effective electric field device. On theother hand, when glass was used as inorganic dielectric, though theaforementioned problem was resolved, it become mechanically brittle,moreover an anti-breakdown strength was also not sufficient, andfurthermore, the shortcoming that the insulator was very easily brokenby local temperature rise caused by application of an alternatingelectric field, could not be obviated.

As described above, in the prior art, since an appropriate material wasnot obtained, the electric field device had a very short life and a highcost, and the way of widely utilizing the electric field device has beenclosed.

One object of the present invention is to provide an electrostatictreatment apparatus of object matters which makes use of a long-life,highly reliable and less expensive electric field device or deviceswhich are free from the above-described difficulties, and to make itpossible to bring the electrostatic treatment apparatus into reallypractical use.

According to the present invention, the aforementioned object isachieved by making an electric field device which is dense, mechanicallyelectrically chemically and thermally durable and highly reliablethrough the steps of employing highly pure and mechanically electricallychemically and thermally extremely durable ceramic materials such as,for example, a high purity alumina porcelain or the like (hereinaftercalled "fine ceramic") as a dielectric material, disposing electrodes onthe shaped material before sintering and sintering the shaped materialintegrally with the electrodes, and by using the made electric fielddevice or devices in an electrostatic treatment apparatus of objectmatter.

With regard to the practical method, a method can be employed, in whichwhen, for instance, high purity alumina porcelain is used, aluminapreliminarily ground into powder having a grain diameter of severalmicrons or less is bound by means of an organic binder, then a rawmaterial sheet formed in a layer shape (called "green sheet") isproduced, on the surface of the green sheet are formed electrodes bymaking use of an ink in which micro-fine powder of appropriate metal,for example, tungsten is dispersed with a thick film printing techniquesuch as, for example, screen printing technique, the thus formed greensheet associated with electrode in itself singly, or after a pluralityof such green sheets have been stacked and press-bonded, the formedmultilayer green sheet, is sintered within an appropriate reducingatmosphere such as a hydrogen furnace at a high temperature in theproximity of 1500° C.

In this case, by making the electric field device from a multilayergreen sheet, it becomes possible to dispose a part of the electrodes asembedded in a sandwich form within the fine-ceramic dielectric in asingle layer or in multiple layers, and thereby it becomes possible toachieve a high degree of electric field effect or ion formation effect,or to enhance a safety by internally embedding an electrode to beapplied with a hogh voltage.

In addition, it becomes possible to effect electrical connection betweenfront and rear surfaces of a monolayer or multilayer structure of fineceramic dielectric layer penetrating therethrough by opening a smallhole penetrating through a green sheet and sintering the green sheetafter filling the small hole also with the aforementioned tungstenmicro-fine powder ink or the like. Accordingly, thereby an electrodedisposed on the front surface of the fine ceramic dielectric layer canbe connected to an electrode for an lead wire disposed on its rearsurface to achieve electrical connection to an external terminal.

For the fine ceramic dielectric material to be used according to thepresent invention, highly pure alumina porcelain having a purity of 90%or higher is preferable, but even among materials other that thatmaterial, any fine ceramic material could be employed so long as it ismechanically, electrically, chemically and thermally durable. When anelectric field device is formed in a multilayer structure, it ispossible to make it less expensive or to enhance its performance byusing a high purity alumina porcelain layer and an alumina porcelainlayer having a relatively low purity and hence being less expensive incombination, by using fine ceramic materials of different kinds havingdifferent natures in different layers or at different locations incombination, or by using a fine ceramic material and the otherdielectric materials (synthetic resin, mica, glass, ERP) in differentlayers or at different locations in combination.

While the surface of the electric field device according to the presentinvention could be used in the produced state, the electric field devicemay be subjected to improvement in the nature of the surface such assmoothening of the surface or creation of electrical conductivity byapplying a suitable glaze on the surface, and in addition, the electricfield device can be subjected to improvements in its surface nature bydepositing a Teflon layer, a silicon layer and a surface layer ofanother appropriate material.

In addition, for the electrode material to be used according to thepresent invention, a high melting point metal that is easily integratedwith the fine ceramic material used as a base material when they aresintered together and that has a coefficient of thermal expansion asclose as that of the fine ceramic material, is preferable, and when thebase material is high purity alumina porcelain, tungsten is mostsuitable. However, depending upon the fine ceramic materials of variouskinds, every suitable metallic material can be selectively used. Upondeposition of the electrode material onto the green sheet, although athick film electrode could be formed through the technique of screenprinting or the like with metal powder dispersed ink, in some cases ametallic electrode which has been preliminarily formed into a wireshape, a sheet shape or a foil shape could be deposited. In addition, athin film electrode deposited by vapor-deposition or the like also canbe used. Furthermore, the electrode material is not always limited to ametallic material, but as a matter of course, every suitable materialsuch as carbon fibers, semiconductor ceramic material or the like can beused. Also the electrode material could have its surface plated withappropriate metal such as nickel for the purpose of preventingoxidation, protecting its surface or facilitating soldering, andmoreover on the electrode itself could be thinly applied a glaze layer,an alumina insulator film or another surface layer.

With regard to the geometrical configuration of the novel electric fielddevice according to the present invention, it can be formed and used notonly in a plane shape but also in an arbitrary curved surface shape(spherical shape, semi-cylindrical shape, circular column shape,polygonal shape, step-like shape, etc.), and when practicing such acurved surface shape, in the stage of a green sheet associated withelectrodes which is still rich in flexibility, the green sheet could beshaped into a desired configuration and then sintered.

The field of application of the electric field device according to thepresent invention extends over every one of charging and/or dischargingapparatuses of object matters and electro-mechanical operationapparatuses of object matters, also the field of application involvesall the subject matters of the Japanese patents and copending Japanesepatent applications as referred to in the beginning of thisspecification, and furthermore, it involves all the methods andapparatuses for application of the electric field device which willappear in the future.

The above-mentioned and other objects, features and advantages of thepresent invention will be better understood by reference to thefollowing description of preferred embodiments of the invention taken inconjunction with the accompanying drawings, wherein:

FIG. 1A is a perspective view showing a top surface of one raw materialsheet in a making process of the electric field device according to thepresent invention,

FIG. 1B is a perspective view showing a bottom surface of the same rawmaterial sheet,

FIG. 1C is a perspective view showing a top surface of the other rawmaterial sheet,

FIG. 1D is a perspective view showing a bottom surface of the other rawmaterial sheet,

FIG. 1E is a perspective view showing the state where the raw materialsheets in FIGS. 1A and 1C are superposed and partly cut away,

FIG. 1F is a transverse cross-section view of the structure shown inFIG. 1E,

FIG. 2 is a cross-section view of one preferred embodiment of anelectrostatic treatment apparatus of object matters according to thepresent invention,

FIG. 3 to 6, 7A and 7B, respectively, are perspective views showingother prepared embodiments of the present invention,

FIG. 8 is a perspective view of a charging treatment apparatus forpowder material according to one preferred embodiment of the presentinvention,

FIGS. 9 to 12 are perspective views and cross-section views of treatmentapparatuses for powder material according to preferred embodiments ofthe present invention,

FIG. 13A is a perspective view of a top surface of a surface layer greensheet in the process for making an electric field device according toanother preferred embodiment of the present invention,

FIG. 13B is a perspective view of a top surface of an intermediate layergreen sheet for making the same device,

FIG. 13C is a perspective view of a bottom surface of the sameintermediate layer green sheet,

FIG. 13D is a perspective view of a top surface of a base layer greensheet for making the same device,

FIG. 13E is a perspective view of a bottom surface of the same baselayer green sheet,

FIG. 14 is a perspective view showing the state where the respectivelayer green sheets were superposed, press-bonded and then sinteredtogether,

FIGS. 15, 16, 17A and 17B are circuit diagrams for an electric fielddevice according to the present invention,

FIG. 18 is a cross-section view of a conveyor machine for powdermaterial embodying the present invention,

FIGS. 19, 20 and 21 are perspective views of various kinds of treatmentapparatus for powder material or the like embodying the presentinvention,

FIG. 22 is a cross-section view of a liquid conveyor apparatus embodyingthe present invention,

FIGS. 23 and 24 are cross-section views of heat pipes embodying thepresent invention,

FIGS. 25, 26 and 27 are cross-section views of powder paintingapparatuses embodying the present invention,

FIG. 28 is a perspective view of an electro-mechanical sortor as anexample of this invention.

FIGS. 29, 30 and 31 are cross-section views of powder conveyorapparatuses according to preferred embodiments of the present invention,

FIGS. 32 to 37 are perspective views of various types of electric fielddevices to be used in an apparatus according to the present invention,

FIG. 38 is a perspective view of an exhaust gas treatment apparatusaccording to one preferred embodiment of the present invention,

FIG. 39 is a cross-section view of a casing for a fluid layer accordingto one preferred embodiment of the present invention,

FIGS. 40 and 41 are perspective views of essential parts of ductcollecting apparatuses according to preferred embodiments of the presentinvention,

FIG. 42A is a perspective view of an electric field device to be used inan apparatus according to the present invention,

FIG. 42B is an enlarged view of a part of the electric field device inFIG. 42A,

FIG. 43 is a cross-section view of an air slide in which an apparatusaccording to the present invention is incorporated,

FIG. 44 is a perspective view of an apparatus incorporating modifieddevices of the electric field device shown in FIG. 42,

FIG. 45A is a cross-section view of an electric field device to be usedin an electrostatic treatment apparatus according to the presentinvention,

FIG. 45B is an enlarged view of a part of the electric field deviceshown in FIG. 45A,

FIG. 46 is a cross-section view of another electric field device to beused in an electrostatic treatment apparatus according to the presentinvention,

FIG. 47 is a cross-section view of an apparatus for supplying electriccharge to a surface of a photo-sensitive material of an electronicphotography incorporating an electrostatic treatment apparatus accordingto the present invention,

FIG. 48 is a cross-section view of an apparatus for supplying monopolarions of predetermined polarity to a target, which is one preferredembodiment of an electrostatic treatment apparatus according to thepresent invention,

FIG. 49 is a cross-section view of an electrostatic chuck incorporatingan electrostatic treatment apparatus according to the present invention,and

FIGS. 50, 51 and 52 are cross-section views of apparatuses for makingcolored toner to be adsorbed on a sheet base material.

FIGS. 1A to 1F show one preferred embodiment of an electric field deviceaccording to the present invention that is operable as an ion source.These figures show a method for making an electric field device, inwhich a group of elongated corona discharge electrodes are disposed on arectangular fine ceramic dielectric plate in its lengthwise direction, asheet of induction electrode having a size opposed to the whole of saidcorona discharge electrode group is embedded within the dielectric plateunder the corona discharge electrode group, and then the entire assemblyis sintered according to the present invention. FIG. 1A is a perspectiveview showing a top surface of an upper green sheet, in which on an uppersurface 2 of the rectangular upper green sheet 1 are formed a pluralityof parallel corona electrodes 3, 4 and 5 directed in the lengthwisedirection of about 1 mm in width and about 100 μm in thickness at aninterval of about 5 mm with ink having tungsten micro-fine powderdispersed therein through a screen printing technique, further theseelectrodes are connected to a common conductor 6 printed through asimilar method, and then a terminal conductor 7 is further connected byprinting.

FIG. 1B is a perspective view showing a lower surface 8 of theabove-described upper green sheet 1, in which a rectangular planarinduction electrode 9 is formed on the lower surface portion opposed tothe entire area of the upper surface occupied by the electrodes 3, 4 and5 by printing with ink having tungsten micro-fine powder dispersedtherein through a similar screen printing technique. FIG. 1C is aperspective view showing an upper surface 11 of a lower sheet 10, inwhich a hole 12 of about 1 mm in diameter is opened at the center of thesame sheet 10 penetrating therethrough, this hole is filled with inkhaving tungsten micro-fine powder dispersed therein to form a conductorpenetrating through the sheet 10, and further a disc-shaped contactingconductor portion 13 of about 10 mm in diameter with the hole 12 locatedat its center, is formed by screen printing similarly with ink havingtungsten micro-fine powder dispersed therein. In addition, through asimilar method, on the left and edge of the sheet 10 is depicted aterminal conductor 7a to be connected with the terminal conductor 7.FIG. 1D is a perspective view showing a lower surface 14 of the lowersheet 10, in which a disc-shaped terminal conductor portion 15 of about10 mm in diameter with the aforementioned hole 12 filled with ink havingtungsten micro-fine powder dispersed therein located at its center, isformed by screen printing similarly with ink having tungsten micro-finepowder dispersed therein. In addition, at the left end of the lowersurface 14 is formed another disc-shaped terminal conductor portion 16of about 10 mm in diameter by screen printing similarly with ink havingtungsten micro-fine powder dispersed therein, and this terminalconductor portion 16 is connected to the terminal conductor 7a through aterminal conductor 17 printed with similar ink. Subsequently,aforementioned respective sheets 1 and 10 are superposed, and after theyhave been shaped by hot press bonding, they are sintered within ahydrogen furnace. Then they are sintered with the planar inductionelectrode 9 airtightly sandwiched between the respective sheets 1 and10, and the electrode 9 can be embedded within a dielectric plate 18which has been integrally sintered from the upper and lower sheets. Andthe aforementioned induction electrode 9 is fused jointly with thedisc-shaped terminal conductor portion 13 and is connected to thedisc-shaped terminal conductor portion 15 on the rear surface of thedielectric plate 18 as conducting through the hole 12. On the otherhand, the group of corona electrodes 3, 4 and 5 on the front surface ofthe dielectric plate 18 are connected through the common conductor 6 andthe terminal conductors 7 and 7a to the disc-shaped terminal conductorportion 16 on the rear surface of the dielectric plate 18. FIG. 1E is aperspective view showing electrode surfaces of an electric field deviceserving as an ion source which was fabricated in the above-describedmanner, in which a ceramic plate portion made of the upper green sheetis partly cut away to show a ceramic plate portion made of the lowergreen sheet and the induction electrode 9. FIG. 1F shows a cross-sectionview of this electric field device. It is to be noted that the surfacesof the electrodes 3, 4 and 5, the conductors 6, 7, 7a and 17 and theterminal conductor portions 15 and 16 are plated by nickel in order toprevent oxidation of tungsten, and thereby soldering of externalconductors to the terminal conductor portions 15 and 16 is facilitated.If a high frequency A.C. high voltage is applied from a high frequencyA.C. high voltage source 19 via the terminal conductor portions 15 and16 not shown between the corona electrode group 3, 4 and 5 and theplanar induction electrode 9 by the intermediary of the fine ceramicdielectric layer 20 (the electrodes 3, 4 and 6 being grounded for thepurpose of safety), then high frequency corona discharge is generatedfrom the edges of the electrodes 3, 4 and 5 along the surface of thedielectric plate 18, and thereby plasma containing plenty of positiveand negative ions is formed. Accordingly, if this device is broughtclose to a proximity of a charged body, ions of the opposite polarity tothat charge are supplied from this plasma to the aforementioned chargedbody, and thereby the charged body can be quickly discharged. In otherwords, the device can be used as a discharger or a charge remover. Inthis case, as a matter of course, repetitive pulse voltages could beapplied by employing a pulse high voltage source in place of the highfrequency A.C. high voltage source 19.

FIG. 2 shows one example in which the ion source electric field device21 in FIG. 1F is utilized to remove electric charge charged by frictionon a rubber belt 23 after passing around a roller 22, in which the ionsource electric field device 21 is disposed in the close proximity of acharged rubber belt surface, and in the illustrated example, negativeions are attracted from the plasma formed by the corona electrode group3, 4 and 5 to neutralize the positive charge on the rubber belt surface.Reference numeral 24 designates a protective resistor.

FIG. 3 shows a ion source constructed by bending the upper sheet 1 shownin FIGS. 1A and 1B about an axis directed in the lengthwise direction ofthe sheet so that the upper surface of the green sheet 1 may comeoutside to form a hollow cylinder 25, and then sintering the hollowcylinder-shaped green sheet. When a high frequency A.C. high voltagesource 19 is connected to the thin wire-shaped corona dischargeelectrodes 3, 4 and 5 which are arrayed on the outer cylindre surface inthe lengthwise direction in parallel to each other and at equalintervals and the induction electrode 9 formed in a cylindrical surfaceshape on the inner cylindre surface as shown in FIG. 3 and then a highfrequency A.C. high voltage is applied between the respective electrodesby the intermediary of the cylindrical dielectric body 25 made of fineceramic, high frequency corona discharge is generated from the thinwire-shaped corona discharge electrodes along the outer surface of theaforementioned cylindrical dielectric body, and thereby plasma isproduced. Accordingly, an electric field device 26 serving as acylindrical plasma ion source can be constructed.

In this case, it is a matter of course that as one modification of thestructure shown in FIG. 3, the thin wire-shaped corona dischargeelectrodes 3, 4 and 5 could be disposed on the cylinder surface so as tobe perpendicular to generating lines. FIG. 4 shows such modification.

FIG. 5 shows an ion source constructed by superposing the upper sheetshown in FIGS. 1A and 1B and the lower sheet shown in FIGS. 1C and 1Dwiht each other, stacking and press-bonding them into the shape shown inFIG. 1E, thereafter bending the assembly about an axis directed in thelengthwise direction of the sheets so that the upper surface having thethin wire-shaped corona discharge electrodes 3, 4, 5, . . . may comeinside to form a hollow cylinder 26, and then sintering the hollowcylinder-shaped green sheet. If a high frequency A.C. high voltage isapplied between the thin wire-shaped corona discharge electrodes 3, 4,5, . . . arrayed on the inner cylinder surface as directed in the axialdirection in parallel to each other and at equal intervals and theinduction electrode 9 embedded within the fine ceramic hollow cylinder26 and formed in a cylindrical surfnce shape via the terminal conductorportions 15 and 16, respectively, as shown in FIG. 5, then highfrequency corona discharge is generated from the corona dischargeelectrode groups 3, 4, 5, . . . along the inner surface of the hollowcylinder 26, and thereby a plasma ion source can be formed. Accordingly,when such a hollow cylindrical electric field device is interposed inthe midway of a pneumatic conveyor pipe line for pulverized or granularmaterial having a high electric resistance, electricity on thepulverized or granular material which has been strongly charged byfriction with the inner wall surface of the pipe line, can beneutralized and removed by ions having the opposite polarity suppliedfrom the plasma produced on the inner surface of the aforementionedhollow cylinder 26.

FIG. 6 shows one modification of the device shown in FIG. 5, in whichthin wire-shaped corona discharge electrodes 3, 4, 5, . . . are arrayedon an inner surface of a hollow cylinder 26 in the directionperpendicular to the axis of the cylinder.

The cylinder-shaped electric field device shown in FIGS. 5 and 6 can beused for removing electric charge of a liquid which has been charged byfriction with a pipe by interposing the device in the midway of a pipeline conveyor of a liquid having a high resistance.

FIG. 7A shows one example of application of electric field devices 27each of which employs its both surfaces as ion sources by providing thinwire-shaped corona discharge electrodes 3a, 4a, 5a, . . . also on thelower surface of the fine ceramic dielectric plate 18 shown in FIGS. 1Eand 1F as directed in the lengthwise direction. In the illustratedexample, the electric field device 27 is directly inserted and disposedwithin a conveyor pipe line 28 for pulverized or granular materialhaving a high resistance or a liquid having a high resistance to removeelectric charge from the pulverized or granular material or the liquid.For the same purpose, the electric field devices shown in FIG. 3 or 4also can be used, and in that case, in place of the planar ion sourceelectric field device 27, these cylindrical ion source electric fielddevices are disposed in the proximity of the center axis of the conveyorpipe line 28 along the center axis.

FIG. 7B shows another example of application of the electric fielddevices, in which a large number of electric field devices 18, 18a, 18b,18c, . . . servicing as ion sources as illustrated in FIGS. 1E and 1Fare disposed on an inner wall surface of a conveyor pipe line 28 forpulverized or granular material or a high resistance liquid so as covera part or whole of the inner wall surface, and electric charge isremoved from the aforementioned pulverized or granular material or highresistance liquid which has been charged by friction with the pipelineon the upstream side by means of the plasma produced by the electricfield devices.

FIG. 8 shows one example in which the planar ion source electric fielddevice 18 shown in FIGS. 1E and 1F is used as a charging apparatus, inwhich the electric field device 18 is insulatively supported inopposition to a grounded non-corona electrode 29 so that the coronadischarge electrodes 3, 4, 5, . . . may be opposed to the non-coronaelectrode 29, and after a plasma has been produced from the coronaelectrodes 3, 4, 5, . . . by applying a high frequency high voltage froma high frequency A.C. high voltage source 19 between the coronadischarge electrodes 3, 4, 5, . . . and the embedded induction electrode9, if the corona discharge electrodes 3, 4, 5, . . . are connected to anegative D.C. high voltage source 30, then negative ions would travelfrom the plasma towards the grounded non-corona electrode 29, andthereby a D.C. electric field and an ion current are produced in acharging space 31 between the electric field device 18 and thenon-corona electrode 29. At this moment, if an object matter intended tobe charged, for intance, pulverized or granular material or a liquiddrop 32 is introduced into this charging space 31, then it is subjectedto bombardment by negative ions, thus negatively charged at once, andsupplied to the exterior as a charged object 33.

FIG. 9 shows one example by application of the electric field device, inwhich negative ions are given to a surface of a grounded photo-sensitiveroller 34 having a photoconductive coating film on its surface, which isused in an electronic photography, by making use of the cylinder-shapedion source electric field devices 26 shown in FIG. 3 or 4. Since theseion sources can produce quite plenty of negative ions uniformly, theycan put negative ions on a photoconductive film 35 on the surface of theroller 34 uniformly within a short period of time. In this figure,reference numeral 19 designates a high frequency A.C. high voltagesource, numeral 30 designates a negative D.C. high voltage source, andsince the effects of these voltage sources are self-explanatory, thereis no need to add special explanation thereon. Reference numeral 26a inFIG. 9 is a similar cylindrical ion source electric field device, inwhich corona discharge electrodes 3, 4, 5, . . . are grounded, so thatpositive ions supplied from plasma formed by this electric field devicecan remove remaining negative ions on the roller 34. Reference numeral19a also designates a high frequency A.C. high voltage source.

FIG. 10 shows one example of application of electric field deviceaccording to this invention wherein a charging ion source electric fielddevice 18 is employed for giving negative charge to a surface ofinsulating film 36 disposed on a grounded non-corona electrode 29,thereby the film 36 is intensely adhered to said non-corona electrode 29due to electric force. The electric field device 18 is moved in thedirection of arrow 37. Thus, the entire surface of film 36 can becharged uniformly. When the D.C. high voltage source 30 is disconnectedand the connecting terminal is grounded, the electric field device 18acts as discharger which removes the surface charges of film 36 andenables said film 36 to be detached from said non-corona electrode 29.

FIG. 11 illustrates an example of employing a charging ion sourceelectric field device 18, as shown by FIG. 8, in a powder paintingapparatus. The charging ion source electric field device 18 is disposedto confront a suspended, grounded substrate 38. Upon forming a plasmaround corona discharge electrodes 3, 4, 5 . . . on the confrontingsurface of electric field device 18 by means of an A.C. high voltagesource 19, a D.C. high voltage source 30 is used to run negative ionsfrom said plasma toward said substrate 38. A powder is concurrently fedfrom above to the surface of electric field device 18 by way of a pipeline 39 and a slit 41 of triangular--formed feeder 18. Thereupon, saidpowder is negatively charged due to bombardment by negative ions and iscarried by electric force toward the substrate 38 to coat a surfacethereof.

FIG. 12 shows an example of application in which an annular ion sourceelectric field device 42 is composed of fine ceramic dielectric inaccordance with this invention and a powder painting apparatus isconstructed by mounting the formed device 42 on the forward end of ahand gun for powder painting. In FIG. 12, the device 42 is shaped as anannular fine ceramic dielectric body with the longitudinal section ofrectangle. Said device 42 has been made so as to have an annularinduction electrode 43 embedded therein and an annular thick film-shapedcorona discharge electrode 44 of tungsten at the front thereof,according to the producing methods as illustrated by FIGS. 1A to 1F indetail. Thus-formed fine ceramic body is aligned with an annular opening46 and attached to the front end of a hand gun 45 made of plastic. Whena high frequency A.C. high voltage from a high frequency A.C. highvoltage source 19 is applied between induction electrode 43 and coronadischarge electrode 44 by way of a protective condenser 47 and a cable48, the annular corona discharge electrode 44 generates a plasma alongthe front surface of annular fine ceramic dielectric body. Further, anegative D.C. high voltage from a negative D.C. high voltage source 30is applied to the point P, as shown in FIG. 12, by way of a protectivehigh resistance 24. Then, negative ions run from said plasma toward thegrounded substrate 38 disposed forward and a D.C. electric field appearsbetween corona discharge electrode 44 and substrate 38. Accordingly,when a powder dispersed in air from a pipe 49 is fed to the rear end ofhand gun 45, the powder which passed from end opening 46 through fineceramic dielectric body 42 is negatively charged by bombardment ofnegative ions mentioned above in the course of spouting to the right.The charged powder is driven by the action of electric field to thesurface of substrate 38 and adheres thereto. As the intensity of ioncurrent can be freely controlled by changing the high frequency A.C.voltage to be applied, it becomes feasible to obtain a good paintingefficiency.

FIGS. 13A to 13E illustrate one embodiment of the electric field deviceaccording to this invention. This embodiment corresponds to "three-phasecontact type electric field curtain device" as the most typical electricfield device for electromechanical operation apparatus. In thisembodiment are employed three green sheets 50, 51, 52 as three layers.FIG. 13A is a perspective view of very thin surface layer green sheet 50having a thickness of about 0.1-0.5 mm when viewed from above sideways.This sheet has no printed electrode. FIG. 13B is a perspective view ofthe upper surface of rectangular intermediate layer sheet 51 having athickness of about 2 mm. On the upper surface, many parallel narrowstrip electrodes 53, 54, 55, 53a, 54a, 55a, 53b, 54b, 55b, . . . aredisposed by screen printing technique with tungsten micro-fine powderdispersion ink. They are of about 1 mm in width and about 0.1 mm inthickness, and are arranged at right angles to the longitudinaldirection if the sheet 51 with equal intervals of about 5 mm. Everythird electrode of them is connected to one another to form threeelectrode groups u, v and w, consisting of electrodes, 53-53a-53b . . ., 54-54a-54b . . . and 55-55a-55b . . . , respectively. The u, v and wphase voltages of a three-phase A.C. high voltage will be applied torespective electrode groups. To this end, three connecting conductors56, 57 and 58 parallel to lengthwise direction of sheet are screenprinted on the back surface of intermediate layer sheet 51 in the samemanner, and the conductor 56 is connected to u-phase group of electrodes53, 53a, 53b . . . on the upper surface of intermediate layer sheet 51by way of small holes 59, 59a, 59b . . . which penetrate through sheet51 and are filled with tungsten micro-fine powder dispersion ink, asshown in FIG. 13C. Similarly, the conductor 57 is connected to v-phasegroup of electrodes 54, 54a, 54b . . . on the upper surface ofintermediate layer sheet 51 by way of similar small holes 60, 60a, 60b .. . . Further, the conductor 58 is connected to w-phase group ofelectrodes 55, 55a, 55b, . . . on the upper surface of intermediatelayer sheet 51 by way of similar small holes 61, 61a, 61b . . . . Thus,the connecting conductors 56, 57, 58 constitute conducting means forapplying u-phase, v-phase and w-phase voltages of a three-phase A.C.high voltage to u-phase group of electrodes, v-phase group of electrodesand w-phase group of electrodes, respectively. FIG. 13D is a perspectiveview of the upper surface of a base layer green sheet 52 of 3 mm inthickness and FIG. 13E is a perspective view of the rear surfacethereof. Reference numerals 62a, 63a and 64a designate small holes whichpenetrate the sheet 52 and are filled with tungsten powder dispersionink. Around said small holes, there are provided disc-shaped contactingconductor parts 62, 63, 64 of about 10 mm in diameter on the uppersurface and disc-shaped terminal conductor parts 66, 67, 68 of about 10mm in diameter on the rear surface. Each of said conductor parts hasbeen screen printed with tungsten powder dispersion ink. Thecombinations 62 - 66, 63 - 67 and 64 - 68 are positioned so as to beconnected by contact to conductors 56, 57 and 58, respectively. Whenthese three green sheets 50, 51, 52 are superposed, press-bonded andthen sintered, a three-phase contact type electric field curtain device69, as shown by FIG. 14, is completed. In this device, there areprovided three-phase electrode groups u, v and w inserted in fineceramic matrix, beneath a smooth thin fine ceramic layer, and, undersaid electrodes, connecting conductors 56, 57 and 58 embedded in thesame fine ceramic matrix, which are connected to u-phase, v-phase andw-phase electrode groups. When three-phase voltages from a three-phaseA.C. high voltage source 70 are applied to three-phase electrode groupsof this electric field curtain device 69 in the sequence u-phase,v-phase, w-phase by way of terminal conductor parts 66, 67, 68, as shownby a schematic diagram of a model in FIG. 15, a progressive wavenon-uniform electric field which travels in the phase sequencedirection, as shown by arrow 72, along surface 71 of device 69 isgenerated. Consequently, if particles of a powder are placed on thesurface 71 of device 69, they are charged by contact with the surfaceand then violently repelled and floated from the surface due to theaction of said progressive wave non-uniform electric field. They areconveyed in floating state in the direction of arrow 72. In summary, themost important electromechanical actions to a powder of this three-phasecontact type electric field curtain device consist in these charging bycontact, repelling and transporting. By virtue of these actions, thiselectric field device can be utilized for preventing the adherence andthe accumulation of powder and for transporting a powder. If the valueof a impressed three-phase A.C. high voltage is being increased, a kindof electrodeless A.C. corona discharge is generated above a certaincritical value of voltage Vc and the air on the surface is electricallydissociated to produce positive and negative ions. In this situation,the above-mentioned electromechanical actions, such as repelling andtransporting, become more vigorous.

Accordingly, when only one electrode group, e.g. u-phase groupconsisting of electrodes 53, 53a, 53b . . . , of these three-phaseelectrode groups of 53, 54, 55, 53a, 54a, 55a, 53b, 54b, 55b . . . isarranged to expose outside (for safety, grounded), as shown by FIG. 16,a vigorous A.C. corona discharge generates around surfaces exposed toair of metal electrode group of 53, 53a, 53b, . . . , even if atrelatively low voltage, and said repelling and transporting actions arepromoted. This device is referred to as one-phase-exposed type.Moreover, modifications of the device in FIG. 16, that is, deviceswherein two phase electrode groups or all three phase groups are exposedare also employable. In addition, with the same three layer structure asshown by FIG. 13 can be formed a so-called single-phase contact typeelectric field curtain device 75 which has single-phase electrodes 73,74, 73a, 74a . . . as shown in FIG. 17A or FIG. 17B, in place ofthree-phase electrodes. In the case when a single-phase A.C. highvoltage from a single-phase A.C. high voltage source 78 is appliedbetween the electrode group 73-73a-73b . . . and the electrode group74-74a-74b . . . , each electrode member of one group being adjacent toelectrode members of the other group, by way of terminal conductor parts76 and 77, as shown by FIGS. 17A and 17B, standing wave A.C. non-uniformelectric field are generated among these electrodes, and particles ofpowder on the surface 71 of device 75 are charged by contact andrepelled violently to float. Although a single-phase contact typeelectric field curtain device 75 has a remarkable repelling action tocharged particles as mentioned above, but generally has no transportingaction. The device of FIG. 17B wherein one group of phase electrodes 73,73a . . . are arranged on the surface 71 to expose to the atmosphere isof one-phase-exposed type and generates a vigorous A.C. corona dischargeat a relatively low voltage to promote remarkably said repelling actionas well. As a matter of course, a single-phase contact type electricfield curtain device in which all electrodes are exposed as modificationof device in FIG. 17A or 17B is operable. Single-phase contact typeelectric field curtain devices of all these types can be employed inconstructing pipe lines for transporting a pulverized or granularmaterial and in lining inner walls of powder painting booth for sweepingoff adhered particles or preventing adhesion of particles. In addition,when these single-phase contact type electric field curtain devices aredisposed obliquely, particles of pulverized or granular material placedon devices are subject to vigorous agitating and floating action andslide downwards along the surface of the device due to gravity.Therefore, the devices can be utilized for conveying pulverized orgranular material. In the device shown in FIG. 15, changes in connectionenable the use of a multiphase A.C. source in place of three-phase A.C.source 70. In the device shown by FIG. 16 also, a multi-phase A.C.source can be used. In such a case, electrodes to be exposed should beexchanged depending on change in phases. In place of using a surfacelayer sheet 50, a thin insulating alumina layer which has been formed byapplying a finely divided alumina dispersion ink onto an intermediatelayer sheet by screen printing and then have been sintered can beemployed. In accordance with this technique, the surface layer 50 can bemade especially thin.

FIG. 18 shows an example of application wherein three-phase contact typeelectric field curtain device as one of electric devices of thisinvention is utilized to compose a conveyor machine for pulverized orgranular material. An underside surface 80 and an upside surface 81 ofinner wall of a flume 79 having rectangular horizontal section are pavedwith a number of plate form three-phase contact type electric fieldcurtain devices 82, 82a, 82b . . . and 83, 83a, 83b . . . which havebeen shown in FIG. 15 or 16. Three-phase A.C. high voltages fromthree-phase A.C. high voltage sources 84, 85 are applied to therespective group of devices and progressive wave non-uniform electricfields which travel in the phase sequence direction as shown by arrow 86are generated. Accordingly, when a powder from a hopper 87 is fed to theleft end 89 of a flume 79 through a chute 88, the powder first contactswith the surface of three-phase contact type electric field curtaindevice 82, is charged by contact, floats under the action of saidprogressive wave non-uniform electric field, and is conveyed in thedirection of arrow 86. By virtue of providing upside surface 81 of innerwall of flume with three-phase contact type electric field curtaindevices 83, 83a . . . , to say nothing of underside surface 80,progressive wave non-uniform electric fields are generated along bothunderside and upside surfaces. Thus, the electric field strength ismultiplied throughout the entire space between both surfaces to enhancewidely the conveying effect. In addition, when a D.C. high voltagesource 92 is connected between neutral points 90, 91 (for example,neutral point of secondary winding or star-connected boostingtransformer) of three-phase A.C. high voltage sources 84, 85 to generatea vertical D.C. field in the flume, the floating effect is usuallyenhanced and, as a result, the transporting capacity increases. Asingle-phase A.C. high voltage source 94 is connected between neutralpoints 90, 91 in place of D.C. high voltage source 92 by changing over aswitch 93 to the right hand, as the case may be. Similar effects areobtained. In such a conveyor, when the A.C. voltages of three-phase A.C.high voltage source 84, 85 is raised above corona initiation voltage Vc,A.C. corona discharges are generated on the surfaces of three-phasecontact type electric field curtain devices 82, 82a . . . and 83, 83a .. . and plasma appears as mentioned above. If the powder has inherentlyan excessive surface charge and tends to coagulate of itself, such apowder is momentarily discharged under the action of plasma generated insaid conveyor during being conveyed. Thus, the powder collected from theright hand end 95 of flume is free-flowing and can be handled with ease.Such a surface modification of powder by plasma is referred to aspassivation. The electric field devices according to this inventionshown in FIGS. 15, 16, 17 and 18 and FIGS. 19, 20 and 21 to be explainedhereinafter can be utilized for passivation operation of powder.

In the case of the conveyor machine shown by FIG. 18, the most importantare underside electric devices 82, 82a . . . and, in many cases, mereunderside devices permit the machine to show a satisfactory conveyingperformance. Thus, upside electric field devices 83, 83a . . . and theelectric sources 85, 92 can be omitted.

The conveyor machine or devices shown in FIGS. 15-18 can transportfibres, sheet materials and liquids, besides powder, not only in thehorizontal direction, but also in an obliquely upward direction and inthe vertically upward direction with ease. The object matters can befurther easily conveyed in an obliquely downward direction.

FIG. 19 shows a cylindrical three-phase contact type electric fieldcurtain device 96 which has been constructed by bending a three-phasecontact type electric field curtain device shown in FIG. 14 of thisinvention as multi-layer green sheet about an axis in the longitudinaldirection so that a cylinder may be formed and the upper surface of saidgreen sheet may come inside of a hollow cylinder. Said device 96 can beused for conveying or passivation-treating an introduced powder, sheetmaterial, fibre, or liquid. In addition, the device can be employed fordischarging these materials. In the device as shown, there are disposedannular three-phase electrodes 97, 98, 99, 97a, 98a, 99a . . .rectangular to the axis of cylinder within dielectric beneath the innerwall surface of cylinder, as depicted by dotted lines. When u-phasevoltage, v-phase voltage and w-phase voltage of three-phase A.C. highvoltage from a three-phase A.C. high voltage source 70 are applied tosaid electrodes by way of terminal conductor parts 66, 67 and 68, aprogressive wave non-uniform electric field is generated, which travelsalong the inner wall of the device 96 in the direction of arrow 72.Therefore, this device can be utilized for various applications asmentioned above. Furthermore, a discharge-chemical treatment (e.g.generation of ozone, oxidation of NO_(x) or SO_(x)) can be performed byforming a plasma within the device 96 and passing a gas therethrough.

FIG. 20 illustrates a modification of the device of FIG. 19 whereingroups of three-phase electrodes 97, 98, 99 . . . are arranged parallelto the axis of cylinder. As a result, a progressive wave non-uniformelectric field which travels along the inner wall in the peripheraldirection, i.e. rotates in a section, as shown by arrow 72 is generated.Accordingly, when powder, sheet material, fiber, liquid or the like isintroduced within the cylinder, said material rotates violently in thedirection of arrow 72 to be subject to mixing action, twisting action,passivation action etc. In the case of fiber, this action is utilizedfor twisting fibers and the resulting product can be removed from theother end of the device. Consequently, the device can be employed inspinning machine. Besides, the device can be used for agitating flame inengine or in combustion chamber to increase combustion efficiency, forperforming discharge-chemical treatment, for promoting chemical reactionby taking advantage of mixing and agitating actions, and for promotingchemical engineering operation, such as drying and material exchange.

FIG. 19 represents another modification of the device shown in FIG. 19or 20, in which groups of three-phase electrodes 97, 98, 99 . . . areobliquely arranged at angle to the axis of cylinder. A progressive wavenon-uniform electric field travels helically along the inner wall ofcylinder from the left end opening to the right end opening as shown byarrow 72. Accordingly, object material, such as pulverized or granularmaterial, fiber, sheet material, and liquid, which is introduced fromthe left end is conveyed helically to the right. In the course ofhelical motion, the object material is subject to an agitating action byrotating and a twisting action. As the device of FIG. 21 is similar infunction to the device of FIG. 20, the device can be employed inchemical and chemical engineering operations, e.g. combustion, drying,material exchange and promoting reaction, and in variousdischarge-chemical treatments.

FIG. 22 illustrates an example wherein one of devices shown in FIGS.19-21 is being used to convey a dielectric liquid. A liquid which isintroduced into a cylindrical three-phase contact type electric fieldcurtain device of this invention through the left end entrance 89 istransported in the direction of arrow 86 by conveying action ofprogressive wave non-uniform electric field, and is expelled from theright end outlet 95. As such a fluid conveying apparatus can be insertedand operated in a medium or location where pressure conveying of fluidby other means is difficult, the apparatus can be used, for example, forembedding in human body to promote the circulation of the blood or thelymph fluid, for embedding in high-tension cable to convey as isolatingcoolant, for conveying a reagent in an analytical instrument, forconveying reaction liquids in a reaction apparatus, and for circulatingand heating liquids in a large-scale tank (e.g. oil tank).

This heating effect accompanied by the conveying effect is one ofremarkable characteristics of this invention. To this end, a kind ofhigh-frequency induction heating is caused within the wall body ofcylindre 96 by selecting a fine ceramic material having large dielectricloss along with increasing frequency of three-phase A.C. current.Otherwise, one, two or three phase groups of three-phase electrodes aresupplied with a different current for heating by Jonle heat. Besideselectrodes for heating can be provided separately from three-phaseelectrodes. When the liquid to be conveyed in itself has a dielectricloss, said liquid is induction heated in the interior, especially in thevicinity of inner wall, of cylinder 96 due to progressive wavenon-uniform electric field, without special provisions mentioned above.As a result, the viscosity of said liquid lowers and the capability forbeing transported of liquid is increased. The device with or withoutsuch provisions is effectively applicable to transporting by pipe ofcrude oil, especially in cold district. The inner wall of transport pipemay be paved with devices of FIG. 15 or 16, or the inner wall itself maybe composed of devices shown by FIG. 22.

In addition, when a mixture of liquids having different densities, suchas oil and aqueous liquid, is introduced into the device of FIG. 20, themixture can be separated by centrifugal force caused by rotating. In thedevice of FIG. 21, separating is performed in the course oftransporting.

On the other hand, the device of FIG. 19 can be utilized to accelerateelectron or ions, provided that the frequency of the source isincreased. The device of FIG. 20 can be utilized for centrifugalseparation due to difference in mass. For example, a gaseous uraniumcompound is ionized and the isotopes are separated.

FIG. 23 shows an example wherein a cylindrical three-phase contact typeelectric field curtain device according to this invention is used tocompose a heat pipe. In the drawing, reference numeral 96 designates acylindrical three-phase contact type electric field curtain device shownin FIGS. 19 and 22. At both ends of device are provided containers 100,101 for working fluid, said containers having the respective heattransfer surfaces 102, 103. When the device 96 is fed with a three-phaseA.C. high voltage from a three-phase A.C. high voltage source 70 by wayof terminals 66, 67, 68 and a progressive wave non-uniform electricfield is generated in the direction of arrow 86, the working fluidcollected in the container 100 positioned in cold part is conveyed tothe right upward along the inner wall of cylinder 96 and flows into thecontainer 101 positioned in hot part. The working fluid in container 101is heated by the heat introduced through heat transfer surface 103 toevaporate, moves then as gas through interior of cylinder 96 in thedirection of arrow 104, and is condensed upon contacting with heattransfer surface 102 of container 100 to collect in the lower part ofcontainer 100. Through this circulation, heat is effectively and rapidlytransmitted from heat transfer surface 103 to heat transfer surface 102.A hot area is cooled by heat transfer surface 103 and a cold area isheated by heat transfer surface 102. As shown by FIG. 24 in this case, acylinder having small diameter may be used as cylinder 96 for conveyingworking fluid and one or more such cylinders may be arranged parallel toeach other within a different cylinder 104a for returning of gas, withthe intention of making the transportation of liquid more effective.Otherwise, a separate cylinder for solely returning gas may be arrangedparallel to and out of the cylinder 96 or cylinders.

FIG. 25 represents an example of application wherein a cylindricalthree-phase contact type electric field curtain device 96 of FIG. 19according to this invention is utilized to compose a powder paintingapparatus for coating the inner surface of a metal pipe. In the drawing,reference numeral 105 indicates a slender transport pipe composed ofsaid electric field curtain device 96. The upper part of the transportpipe has a hopper section 106 which is also composed of three-phasecontact type electric field curtain device having three-phase electrodegroups. The lower part of the transport pipe has a corona dischargeelectrode 107 of needle form which protrudes within a metal pipe 108 tobe painted. Said discharge electrode 107 is insulated from transportpipe 105 and is attached to the tip thereof. A negative D.C. highvoltage from a D.C. high voltage source 109 is impressed on said coronadischarge needle by way of a high-tension cable 110 attached to theoutside surface of transport pipe 105. The corona discharge needle emitsa negative corona discharge toward the inner surface of grounded metalpipe 108. Reference numeral 70 denotes a three-phase A.C. high voltagesource. A three-phase A.C. high voltage therefrom is impressed ontransport pipe 105 and on hopper section 106 by way of terminals 66, 67,68, and progressive wave non-uniform electric fields in the directionsof arrows 111, 112 are formed along the inner walls thereof. When apowder of a thermoplastic resin is fed into the interior of hoppersection 106 from a powder tank 113 via a feed pipe 114 and a dispersingcone 115, said powder is transported downward within cylinder 105 underthe action of said progressive wave electric field and, at the lower endof the cylinder, is negatively charged by negative ions given fromcorona discharge needle 107. The negatively charged powder is driven byan electric field between discharge needle 107 and metal pipe 108 andadheres to inner wall of metal pipe 108 to stack. Consequently, when themetal pipe 108 is allowed to descend gradually in the direction of arrow116, an electrostatic accumulation layer of plastic powder iscontinuously formed on the inner surface of metal pipe. Accordingly,when the metal pipe 108 is pulled down to separate completely from thetransport pipe and is heated, said layer of plastic powder is fused toform a coating on the inner surface.

FIG. 26 represents an example of application wherein a three-phasecontact type electric field curtain device 75 of one-phase-exposed typeshown in FIG. 17B according to this invention is employed in anelectrostatic powder painting apparatus. In the apparatus, said deviceswhich are so disposed that the surfaces 71 provided with electrodes mayface always inward constitute vertical walls 117, 118 and lower inclinedwalls 119, 120. Each of devices is fed with a three-phase A.C. highvoltage, which is higher than the corona initiation voltage Vc, from athree-phase A.C. high voltage source 70. In addition, a D.C. highvoltage which comes from a grounded D.C. high voltage source 30 and isless higher than that of the earth is applied to the neutral point ofthe source 70. While a substrate 122 suspended from a grounded rail 121above descends into the interior of the apparatus, a powder isintroduced from the lower end by way of a pipe 123 and a T-formed inlet124. The powder is conveyed upward along inclined walls 119, 120 underthe action of the progressive wave non-uniform electric field in theapparatus, and then is elevated along vertical walls 117, 118. In themeantime, a negative ion current passes by action of D.C. field fromplasma generated along inner faces of inclined walls 119, 120 andvertical walls 117, 118 to substrate 122. The powder is negativelycharged by bombardment of said negative ion current, and is driven underthe action of D.C. field to the surface of grounded substrate 122 toadhere thereon. Particles which have not adhered fall downward and areconveyed upward in the same manner as mentioned above, to re-enter intocoating operation. Upon completion of operation, the coated substrate122 is introduced in an oven and baked to form a finished paint coatingon the surface.

FIG. 27 shows an example of application wherein three-phase contact typeelectric field curtain devices 69 shown by FIG. 15 or 16 of thisinvention are employed to pave the entire inner wall of a booth 126 forpowder painting, and are utilized for sweeping off powder particlescollected and adhered on the inner walls of booth in order to conveythem to a recovery trough for collecting. In FIG. 27, reference numerals127-138 indicate said devices used in paving inner wall of booth 126. Itis so constructed that, upon closing a switch 139, the devices areconnected to a three-phase A.C. high voltage source 70 and pregressivewave non-uniform electric fields are caused to travel in the directionof arrows 147-145. When this is a case, all powder layers 147-150adhered on inner wall are violently peeled and repelled by the action ofsaid progressive wave non-uniform electric field and are conveyeddownward, said powder layers having been built up by particles remainingof charged painting powder ejected from a spray gun 146 against agrounded substrate 122. The conveyed powder is collected on electricfield curtain devices 151 for horizontally transporting, with which anunderside trough is paved. Then, the switch 152 is closed. Thereupon, ahorizontal progressive wave non-uniform electric field is generated inthe direction perpendicular to the plane of the section by closing aswitch 152. By virtue of generated field, powder particles on electricfield curtain devices 151 are conveyed to an outlet 153 to collect in arecovery trough.

FIG. 28 represents an example of application in which three-phasecontact type electric field curtain devices 69 of FIG. 15 or 16 are usedto construct an electromechanical sorter for separating a powder mixtureconsisting of three different ingredient powders. In FIG. 28, referencenumeral 153 designates a plate which has been constructed with devices69 shown in FIG. 15 or 16 and is so inclined that this side of plate maybe lower. Each of three-phase electrode groups is arranged so as toalign with the direction of inclination, as shown by a dotted line. Theu-phase voltage, the v-phase voltage and the w-phase voltage of athree-phase A.C. high voltage from a three-phase A.C. high voltagesource 71 are impressed in phase sequence as shown in FIG. 28. As aresult, a progressive wave non-uniform electric field which travelsalong the surface of plate 153 to the right is generated as repeatedlymentioned above. However, this electric field can be split into numerousrotating progressive waves which travel to the right or to the left,such as primary rotating progressive wave toward right (first mode),primary rotating progressive wave toward left (second mode) andsecondary rotating progressive wave toward right (third mode) . . . .Among charged particles, ones which can not follow anyone of waves dueto particle's characteristics determined by particle' s diameter, mass,and charge remain rotating without travelling. Particles capable offollowing the first mode are carried to the right. Particles capable offollowing the second mode are carried to the left, and so forth. Thus,when a mixture of three different powders of aforementioned particletypes is dropped on upper central part plate 153 from a hopper 113through a feed pipe 114, particles of first type roll down straightalong the inclined plane of plate 153 and are collected in a hopper 155.Particles of second type are carried to the right during rolling downand enter a right-hand chute 156. Particles of third type are carried tothe left during rolling down and enter a left-hand chute 157. Thus,three different ingredients of a powder mixture can be completelyseparated merely by an electro-mechanical procedure.

FIG. 29 represents a modification of the three-phase contact typeelectric field curtain device shown in FIG. 15, in which powderparticles being conveyed receive simultaneously monopolar charges toenhance the conveying effect. Each of three-phase electrodes 57, 58, 59. . . is divided into two electrodes, i.e. a pair of electrodes. such as57a and 57b, 58a and 58b, 59a and 59b, as shown on the drawing. A pairof one phase electrodes a and b are connected each other by an insertedhigh resistance. U-phase, v-phase and w-phase voltages are applied topairs three-phase electrodes 57a-57b, 58a-58b, 59a-59b . . . byconnecting to a three-phase A.C. high voltage source 70 via terminals66, 67, 68. A progressive wave non-uniform electric field which travelsin the direction of arrow 72 on the surface 71 is generated. Thereupon,a pulse high voltage from a pulse high voltage source 161 is appliedbetween paired electrodes a, b of the same phase within a period of timewherein the potential of said pair of the same phase is less or morehigh than both those of adjacent pairs of electrodes. As a result, anelectrodeless pulse corona discharge is generated in gaseous space abovesaid pair to produce plasma. From this plasma are emitted monopolarnegative or positive ions toward adjacent electrodes. These ions bombardparticles of pulverized or granular material or liquid from above tocharge them negatively or positively. Simultaneously, said particles areconveyed in the direction of arrow 72. By this modification, it hasbecome feasible that a material to be conveyed is always intenselycharged and is more effectively conveyed.

FIG. 30 shows a modification of the electric field device in FIG. 29.Grounded corona discharge electrodes 162, 163, 164 . . . of thin wireshape which protrude from surface 1 into the gaseous space above aredisposed between every paired electrodes of same phase 57a-57b, 58a-58b,59a-59b . . . . As a result, a more intense corona discharge isgenerated and a charging performance increases, as compared with thecase when a pulse high voltage is applied between paired electrodes a,b. It results in enhancement of conveying effect.

FIG. 31 shows an example of application wherein electric field devicesshown in FIGS. 1E and 1F, or 17A and 17B are employed for conveying apulverized or granular material. The underside and the upside of aninclined flume having rectangular section are paved with said electricfield devices 166, 166a . . . and 167, 167a . . . respectively.Single-phase A.C. high voltages from single-phase A.C. high voltagesources 168, 169 are applied to underside electrodes and upsideelectrodes, respectively. A standing-wave non-uniform alternatingelectric field is formed on the surface, which faces the interior of theflume, of respective electrode group. When a pulverized or granularmaterial is fed to an inlet 170 situated on the left-hand side above,the material advances into the flume, contacts immediately with electricfield device group 166, 166a . . . , is charged by contact, is violentlyrepelled to float, is conveyed to the right downward as shown by arrow171, and finally is expelled through an outlet 172. In this case, if aD.C. high voltage source 173 or an A.C. high voltage source 174 isinserted between the neutral points of output side or between outputterminals of A.C. sources 168, 169 by way of a switch 175, a D.C. highvoltage electric field or an A.C. high voltage field is generatedbetween electric field device groups 166, 166a . . . and 167, 167a . . ., and said conveying action is widely increased. In this case also, whenA.C. output voltages of sources 168, 169 are increased above the coronainitiation voltage Vc at the surfaces of said electric field devices toform plasma on the surfaces, the conveying action is enhanced. As thecase may be, the flume 165 is provided only with underside electricfield devices 166, 166a . . . . The upside devices 167, 167a . . . andthe electric sources 169, 173, 174 can be omitted.

Furthermore, in the case of aforementioned electric field devices(including devices of FIG. 1E, FIG. 1F, FIG. 5, FIG. 6, FIG. 7, FIG. 8,FIG. 11, FIG. 14, FIG. 15, FIG. 16, FIG. 17A, FIG. 17B, FIG. 18, FIG.19, FIG. 20, FIG. 21, FIG. 22, FIG. 25, FIG. 26, FIG. 27, FIG. 28, FIG.29, FIG. 30 and FIG. 31), the air above the surface of device can bereplaced by an inert gas, such as N₂, CO₂, H₂ O and combustion gases, inorder to prevent ignition of a material to be conveyed. A dry gas can befed for increasing conveying effect. A mechanical vibration of electricfield device may be caused by a suitable vibrator for promotingtransportation. Optionally, an electric field device is provided with alarge number of small holes penetrating through device itself to feed agas from the back side to the upper surface of device, for promotingrepelling and floating of particles by hydrodynamic means.

FIGS. 32-37 represent electric field devices as ion source, wherein avery long transmission line or lines are disposed on a surface of a fineceramic dielectric body as linear corona discharge electrode, one end ofsaid transmission line being provided with an input terminal for apply avoltage. This structure of discharge electrode is especially appropriatefor using a very short-time pulse high voltage of about 1 ns-1000 ns inpulse length as impressed voltage. In this case, a pulse voltage runsfrom input end as progressive wave with generating intense pulse coronadischarge, and plasma is formed. A discharge caused by pulse highvoltage having such a steep rise has an especially activedischarge-chemical action, and is suitable to be utilized in an ozonizeror in oxidation of NO_(x), SO_(x) or the like.

In the embodiment shown in FIG. 32, two parallel long transmission lines176, 177 of narrow strip form as linear corona discharge electrode(hereinafter, referred to as "corona transmission line") are disposed tomeander on a rectangular fine ceramic dielectric plate 1, in accordancewith the method of invention. The aforementioned very short-time pulsehigh voltage from a very short-time pulse high voltage source 180 isimpressed on the device via its input terminals 178, 179. The impressedvoltage propagates along transmission lines 176-177 to the ends 181,182. In the course of this propagation, an active plasma as mentionedabove is generated between transmission lines 176 and 177. When the ends181, 182 are open as shown on the drawings, a progressive wave voltageis reflected. However, when a resistance equal to surge impedance oftransmission lines is inserted between both ends, the reflection will beeliminated.

FIG. 33 represents a modification of the device in FIG. 32, in whichelectrodes 176, 177 are disposed in interdigitated relation, as shown onthe drawing. In this case, the progressive wave travels as shown byarrows 183-184-185 . . . to the end 186.

FIG. 34 shows an electric field device produced by technique depicted byFIGS. 1 wherein a planar induction electrode 9 is embedded within arectangular fine ceramic dielectric plate 18, and along linear coronadischarge electrode 187 of strip form is arranged on a surface 2 ofdielectric plate 18 to meander, so that parts of the line may beparallel to each other and equidistant, whereby electrode 187 and planarinduction electrode 9 beneath it form transmission lines via dielectriclayer. When said very short-time pulse high voltage is applied betweenterminals 178 and 179, a progressive wave high voltage runs as shown byarrows 188-189-190 . . . to the end 191. While the voltage waveproceeds, a creeping corona discharge is generated along surface 2 ofdielectric body from the corona discharge electrode 187 of narrow stripform to both sides thereof and an active plasma as referred to aboveappears.

FIG. 35 shows a cylindrical electric field device 192 which has beenconstructed by bending an electric field device of FIG. 34 about alengthwise directed axis, so that the upper surface may come inside.FIG. 36 shows a similar cylindrical electric field device 193 which hasbeen constructed bending the same, so that the upper surface may comeoutside. In these devices, an active corona is generated along the inneror outer surface, respectively.

FIG. 37 illustrates a modification of electric field device in FIG. 36wherein a long linear corona discharge electrode is arranged to formhelix on the surface of a fine ceramic cylinder 193. Transmission linesare formed by a cylindrical induction electrode embedded within cylinder193 and the helical corona discharge electrode 194. When a veryshort-time pulse high voltage is applied between two said transmissionlines by way of terminals 178, 179, a progressive wave travels withdepicting a helix along electrode 194, and active coronas are generatedon right and left sides of electrode. In this embodiment, the electrode194 is printed on the outer surfnce of green cylinder which has beenshaped from a green sheet.

FIG. 38 illustrates an apparatus in which electric field devicesaccording to this invention are employed as ion source. The apparatuscan be utilized for oxidizing SO_(x), NO_(x) etc. in waste combustiongases from motorcar engine, boiler etc., or for generating ozone. In theapparatus, a number of electric field devices, e.g. shown in FIG. 1E,FIG. 1F, FIG. 17A, FIG. 32, FIG. 33 and FIG. 34, especially electricfield devices 195 of FIG. 34 having long corona discharge electrodes 187of narrow strip form on both surfaces of a fine ceramic dielectric plate18, are arranged parallel to the gas current in a gas duct 196. A veryshort-time pulse high voltage is applied between corona dischargeelectrode 187 of narrow strip form and embedded planar inductionelectrode 9 of each electric field device 195 from a very short-timepulse high voltage source 180 by way of terminals 178, 179. Thus, activeplasma is generated on both sides of all electric field devices 195.When a waste combustion gas containing noxious componants, such asSO_(x) and NO_(x) is passed through the duct 196 from inlet on this sidein the direction of arrow 197, these components are oxidized due todischarge-chemical action of said plasma to form SO₃ and NO₂, which areeasily removed by wet process. In addition, when a minute amount ofammonia is added to said waste gas at the entrance, ammonia combineswith said components to generate an aerosol of double salts of ammoniumsulfatenitrate. Thus-formed aerosol can be easily collected by means ofan electrostatic precipitator arranged downstream to remove.Furthermore, if a layer including an ingredient having catalytic actionis disposed on surfaces of fine ceramic dielectric body of each electricfield device 195, NO_(x) and NH₃ can be double decomposed to obtain N₂and H₂ O. On the other hand, when dry air or oxygen is introduced as gasto be treated into the apparatus, ozone can be generated. For thispurpose, each planar induction electrode 9 embedded in fine ceramicplate should be formed hollow and air or water should be passed throughthe interior of electrode to cool each electric field device 195.

In the apparatus shown in FIG. 38, any of electric field devices havingcylindrical shape or any other shape according to this invention, suchas those illustrated in FIG. 3, FIG. 5, FIG. 5, FIG. 6, FIG. 35, FIG.36, and FIG. 37, can be effectively disposed in the gas duct 196 inplace of an electric field device 195 of plate shape.

FIG. 39 illustrates an example of application wherein a number of,electric field devices according to this invention, as ion source, aredisposed in a fluidized bed 199 of a powder of a material having highresistivity for preventing intense electrification of particles due tofluidization and adhesion of particles to wall. In the drawing,reference numeral 198 designates a fluidized bed vessel in which slitsfor gas flow, e.g. perforated plate 200, are laid in the lower part. Agas from a gas inlet 201 is forced to pass through said perforated plate200 and fluidizes a powder of a material having high resistivity in thespace 202 above said plate to form a fluidized bed 199. Referencenumerals 203, 203a designate electric field devices of FIGS. 1 as ionsource, which are disposed along the inner walls of vessel 198.Reference numerals 204, 204a . . . designate electric field devices 27of FIG. 7A having corona discharge electrodes of strip form on bothsides as ion source, which have been installed vertically, equispaced,and parallel to one another in the space 202. By application of an A.C.high voltage from an A.C. high voltage source 19 between the coronadischarge electrode and the embedded planar electrode of each of allabove-mentioned electric field devices, plasma is formed on externalsurfaces of the devices. The charge of powder which has been caused byfluidization in the space 202 is removed by virtue of formed plasma, andadhesion of particles to inner walls of vessel 198 by electric force aswell as any coagulation of powder itself is effectively prevented.

FIGS. 40 and 41 illustrate examples of application wherein an electricfield device of this invention is used as ion source in an electrostaticprecipitator. Although all ion source electric field devices mentionedabove can be employed for the purpose, the device shown by FIG. 34 isused in these examples.

FIG. 40 represents a single-stage electrostatic precipitator from whicha duct for gas passage is removed. Reference numerals 205, 206 denotegrounded plate form dust collecting electrodes. Reference numeral 207denotes an ion source electric field device illustrated in FIG. 34 whichhas a long corona discharge electrode 187 of strip form on both surfacesof a fine ceramic dielectric plate 18. A planar induction electrode 9embedded within body and a corona discharge electrode 187 are equal inD.C. potential because of both electrodes being connected to a highresistance 208 by way of terminals 179, 178. In addition, a negntiveD.C. high voltage is applied to planar induction electrode 9 and coronadischarge electrode 187 by connecting the terminal 178 to a negativeD.C. high voltage source 210 via an inductance 209, in contrast withgrounded dust collecting electrodes 205, 206. Reference numeral 180denotes a pulse high voltage source which applies a pulse high voltagebetween terminals 178 and 179 by way of coupling condensers 211, 213,and thereby causes corona dischage electrode 187 to generate creepingpulse corona discharge along surfaces on both sides of ceramicdielectric body 18. Thus, a planar plasma ion source is formed. Negativeions are removed from this plasma ion source under the action of a D.C.electric field formed in dust-collecting spaces 213, 214 between coronadischarge electrode 187 and dust collecting electrodes 205, 206, andflow toward duct collecting electrodes 205, 206. When a dust laden gasis introduced into dust-collecting spaces 213, 214 in the direction ofarrow 215, duct particles in gas are bombarded by said negative ions andare intensely, negatively charged. The negatively charged particles areimmediately separated and collected on the surfaces of dust collectingelectrodes 205, 206 by coulomb force. The clean gas is expelled outsidein the direction of arrow 216. Dust particles collected on the adheredto dust collecting electrodes 205, 206 are released by hammering to fallinto a lower hopper not shown in the drawing. Inductance 209 inhibitsthe applying of pulse voltage to a negative D.C. high voltage source210.

FIG. 41 shows a two-stage electrostatic precipitator from which a ductfor gas passage is removed. Reference numeral 217 denotes a chargingsection having a structure similar to that shown in FIG. 40, but thesize in the direction of gas flow being short. In this charging section,dust paticles of a dust laiden gas flowing in the direction of arrow 215are negatively charged. Reference numeral 218 denotes a collectingsection comprising a group of parallel planar electrodes 219, 220, 221,222, 223 . . . . Every other electrode 219, 221, . . . is grounded. Theremianing intermediates electrodes 220, 222 . . . are insulated and anegative D.C. high voltage is applied to them by a D.C. high voltagesource 224. Consequently, uniform D.C. electric fields are formed indust-collecting spaces between grounded electrodes 219, 221 . . . andnegative D.C. high voltage electrodes 220, 222 . . . . When dustparticles which have been negatively charged in the charging section 217flow into the collecting section with floating in gas, said dustparticles are immediately separated and collected on grounded electrodes219, 221 . . . having, so to speak, positive polarity. Cleansed gas isexpelled out side in the direction of arrow 216.

In the apparatus shown in FIGS. 40, 41, a planar ion source, as ionsource, can be formed by virtue of utilizing an electric field device offine ceramic body according to this invention. Thus, the chargingefficiency and the dust-collecting efficiency resulting therefrom can beremarkably increased, as compared with the case when a prior coronadischarge electrode of strip form is used.

Various electric field devices according to this invention can beprovided with a number of small holes penetrating through the device andthereby permit to feed air, a gas or a liquid from back side to frontthrough said small holes. By this menas, the adhesion of a powder to thesurface can be prevented and any electromechanical effects for handlinga powder, such as repelling, floating and transporting, are enhanced.When this electric field device is employed for promoting a reaction,the small holes can be utilized as inlet for an object gas. In somecases, an electric discharge is caused within small hole to obtain aspecial effect. In certain cases, an inert gas is fed to an electricdischarge area through small holes to prevent ignition and explosion dueto discharge. These are examples of numerous possible applications.Thus, the provision of small holes penetrating through the deviceconstitutes one important feature of this invention.

FIGS. 42 show an example of above-mentioned perforation applied to theelectric field device shown in FIGS. 1A-1F. FIG. 42A is a perspectiveview of a perforated electric field device, partly showing a section.FIG. 42B is a detail drawing of a part about a small hole. An electricfield device shown in FIG. 42A has a large number of equidistant smallholes 226 in the areas between strip-shaped corona discharge electrodes3 and 4, 4 and 5 . . . . To make this device, corona dischargeelectrodes are printed on the upper surface of upper layer green sheet 1as mentioned in the explanation of FIGS. 1A-1F. In screen printing ofplanar induction electrode 9 on the lower surface of upper layer greensheet 1, it is necessary to leave a circular not printed area 225 aroundevery pre-determined position of said small hole, the diameter of saidcircular not printed area being larger than that of small hole to beprovided. Thereafter, an upper layer green sheet 1 and a lower layergreen sheet 10 are press bonded. Then, small holes 226 are formed bypunching, and the whole is sintered. When air or gas is ejected in thedirection of arrow 227 from below through small holes 226 of thus-formedsintered ceramic dielectric plate 18 onto the upper surface 2 thereofwhere plasma is generated around corona discharge electrodes 3, 4, 5 . .. , the aforementioned effects can be obtained. Small holes 226 may bearranged within corona discharge electrodes 3, 4, 5 . . . . In any ofthese cases, an induction electrode 9 should have a vacent circle arounda small hole 226, the diameter of said circle being larger than that ofsmall hole, in order to prevent exposing of induction electrode 9 to thesmall hole. Thereby, an occurrence of spark between induction electrode9 and electrode 3, 4 or 5 can be inhibited.

FIG. 43 represents an air slide conveyor composed of three-phase contacttype electric field curtain devices of one-phase-exposed type, as shownin FIG. 16, which are provided with a number of small holes. In thedrawing, reference numeral 69 denotes a three-phase contact typeelectric field curtain device of one-phase-exposed type. Upon applying athree-phase A.C. high voltage from a three-phase A.C. high voltagesource 70 to electrodes 53, 54, 55, 53a, 54a, 55a . . . by way ofterminals 66, 67, 68, a progressive was non-uniform electric fieldtravelling in the direction of arrow 228 is generated. Reference numeral226 designates many small holes disposed in every space betweenelectrodes of electric field device 69. Air is spouted through saidsmall holes 226 toward above the device when air is forced to flowthrough an inlet 230 to an air chamber 229 arranged beneath small holes226. When electric field curtain devices 69 are arranged on theunderside of flume 231 and a powder is made to fall from an inlet 232located on the left side above, the powder immediately contacts with theupper surface of electric field curtain device 69 to charge and isrepelled. The repelled particles of powder float under the combinedactions of said progressive wave non-uniform electric field and saidspouted air, are conveyed in the direction of arrow 228, and areexpelled out from an outlet 223. In this case, floating and conveyingare widely enhanced by the action of spouting air. Furthermore, whereasa usual air slide conveyor is provided with a slant and conveyingobliquely downward only is possible under the action of gravitationalforce, conveying obliquely upward, to say nothing of horizontally, ispossible with this embodiment of this invention. If a suitablepreliminary charging device is disposed within inlet 232 to chargepreliminarily to entering powder, charging of powder by contact with theelectric field curtain device 69 becomes unnecessary. Thus, a powderhaving high adherence or a wet powder can be conveyed withoutcontacting.

FIG. 44 shows a modification of device shown in FIG. 42, wherein anumber of slits are provided in place of small holes. This electricfield device 234 is composed of many modules 235 arranged parallel andequidistant. This module 235 comprises a rectangular fine ceramicdielectric body 236 having rectangular cross section. Said dielectricbody has an induction electrode 237 embedded in itself, and filmyelectrodes 238, 239 on both sides. The sharp upper edges 240, 241 ofsaid filmy electrodes constitutes corona discharge electrodes. When anA.C. high voltage is applied between the electrodes 238, 239 and anembedded induction electrode 237 from an A.C. high voltage source 19 viaterminals 15, 16, a creeping corona discharge runs from sharp upperedges 240, 241 inward along the upper surface of dielectric body 236 andplasma as ion source is generated. A space 242 between two modulesadjacent to each other serves as a slit for passing air or a gas in thedirection of arrow 243. Thus, the device 234 has a function quitesimilar to that of device in FIGS. 42.

FIG. 45A represents another example of structure of perforated electricfield device, which has a planar electrode 245 on the upper surface of afine ceramic dielectric body plate 244 and further another planarelectrode 246 embedded in the body. In addition, a number of small holes266 penetrates through these planar electrodes 245, 246 and the fineceramic dielectric body plate 244. In this instance, inner peripheralparts 247, 248 of electrodes 245, 246 are exposed to the interior ofsmall holes 226, as shown by FIG. 45B. When a very short-time pulsehaving voltage from a very short-time pulse high voltage source 180 isapplied between both electrodes, a creeping corona discharge isgenerated along the inner wall surface of small hole 226 between innerperipheral parts 247 and 248. This corona dicharge acts as plasma ionsource to feed ions on the upper surface of the dielectric body plate244. If air or a gas is passed upward through small holes 226 frombelow, various aforementioned effects are obtained.

FIG. 46 shows a modification of the device shown in FIG. 45, in whichthe fine ceramic dielectric body 244 has a planar electrode 245a also onthe lower surface thereof. Thus, the discharge along the inner surfaceof small hole 226 is directed upward and downward from peripheral part248. Therefore, when a gas is fed through small holes 226, adischarge-chemical action is doubled, as compared with that in thedevice of FIG. 45. On the other hand, when a charged liquid is passedthrough small holes 226, the electric charge is effectively removed.

FIG. 47 represents a modification of the device shown by FIG. 46 whereina very short-time pulse high voltage from a very short-time pulse highvoltage source 180 is applied between an upper planar electrode 245 andan inner embedded planar electrode 246 by way of terminals 15, 16 togenerate plasma in the upper half of every small hole 226, andadditionally a D.C. high voltage from a D.C. high voltage source 249 isapplied between electrode 246 and lower planar electrode 245a viaterminals 16, 250, thereby a monopolar ion supply source is constituted,which feeds downwardly selectively negative ions in the case of wiringshown in FIG. 47. This device is employable for supplying charges ofrequired polarity, i.e. negative or positive, uniformly on the surfaceof photosensitive material having photoconductivity for an electronicphotography. When this is a case, the intensity of current can bemodified as desired by changing the voltage of the D.C. voltage source249.

FIG. 48 shows an apparatus using a modification of the device in FIG. 47wherein separnte annular discharge electrodes 251, 252, 253 . . . aredisposed around respective small holes so that the inner peripheral partof electrode may be exposed to the interior of small hole, in place ofthe upper planar electrode 245. When a signal pulse high voltage from apulse source 257 is applied between the embedded planar electrode 246and each of said annular electrodes by way of terminal 16 and terminals254, 255, 256 . . . to generate a plasma in the upper half of each smallhole, monopolar ions of prescribed polarity (in this embodiment,negative) are attracted downward under the action of a D.C. electricsource 249 and reach a target 259 placed below to which a further higherpotential is applied from a D.C. electric source 258. Assuming that thetarget 259 is a surface of a rotating drum composed of photosensitivematerial having photoconductivity, an electrostatic latent image of aletter (or a pattern) consisting of dots can be formed on the surface259 by giving pulse signals corresponding to said letter to terminals254, 255, 256 . . . . After a toner is electrostatically displacedthereto, the image is transferred on a paper and fixed to form anelectronic photograph.

FIG. 49 shows a structure of an electric field attaching apparatus, orelectrostatic chuck for attaching and fixing paper, plastic sheet,machine part etc., wherein an electric field device illustrated in FIGS.1A-1F is used. Reference numernl 18 in the drawing denotes a fineceramic dielectric plate having a slight electric conductivity.Electrodes 3, 4, 5 . . . of strip form are disposed on the surface ofthe plate and a planar induction electrode 9 is embedded in said fineceramic dielectric plate. A D.C. voltage is applied thereto from a D.C.electric source 30 via a switch 260. When an object 261, such as paper,sheet material and machine part, is attached to the right-hand surfaceof the plate, negative charge is transferred from electrodes 3, 4, 5 tothe object 261 and appears on the surface confronting the dielectricplate 18 of the object 261. Said negative charge is attracted by theinduction electrode 9 of positive polarity so that the object is firmlyfixed on the dielectric plate 18. If a switch 260 is changed over to theearth side, the object 261 loses immediately the attracting force to bedetachable.

FIG. 50 shows one example of application of electric field attachingapparatus 18 shown in FIG. 49. On said attaching apparatus is attached asheet of paper or a plastic sheet material 261 to fix. When a picture orletters are written on the plastic sheet material 261 by means of amagnetic brush 263 which has been formed by attracting an iron powerhaving adhered coloring toner particles with a grounded magnet 262,coloring toner particles attached to iron powder by charging due tocontact are transferred onto the sheet material 261 under the attractingaction of the planar electrode 9. After removing the sheet material fromthe apparatus 18, it is heated by irradiating with infrared ray or thelike method. The picture or letters on the sheet material 216 are fixed.Such an image forming can be achieved in the same manner, even ifelectrodes 3, 4, 5 of strip form are eliminated from the surface ofceramic dielectric plate 18. FIG. 51 shows a modified apparatus asmentioned above. As illustrated in FIG. 52, when a picture or lettersare written on a sheet material 261 with a grounded metal pen, negativecharge passes from the metal pen onto the sheet material 261 and anelectrostatic latent image corresponding to said picture or letters isformed. After releasing the sheet material from the device 18, thesurface of sheet material is swept with a magnetic brush includingtoner. As a result, the toner is transferred onto the electrostaticlatent image to develop. When heated, a fixed picture or fixed lettersare formed on sheet material 261.

The operation of the device composed of fine ceramic according to thisinvention is frequently accompanied by heating. For example, when it isintended that a viscous liquid is conveyed through the device forconveying liquid shown in FIG. 22, viscosity of the liquid lowers byheating a cylindrical three-phase contact type electric field curtaindevice 96, and conveying will be performed without difficulties. To thisend, separate currents for heating may be supplied to electrodes forforming electric field from a different D.C. or A.C. electric source, orelectromagnetic induction may be utilized. Heat is generated inelectrodes due to Joule heat. This is also an important feature of thisinvention.

Especially in the case of application shown by FIG. 22, the cylindricalelectric field device 96 which is the same as that of FIG. 19 may besurrounded by a coil. When a high-frequency A.C. current flows throughsaid coil, different high-frequency A.C. currents flow in annularelectrodes 97, 98, 99, 97a, 98b, 99c . . . , to perform easily heating.

What is claimed is:
 1. A method of making a high voltage electric field device used for the formation of a corona discharge comprising:providing a first raw sheet of a fine high purity alumina ceramic dielectric material, the first sheet including opposite upper and lower surfaces; printing a linear electrode on the upper surface of the first sheet of fine high purity alumina ceramic dielectric material with a dispersion ink of a finely divided tungsten metal; printing a planar electrode on the lower surface of the first sheet with said dispersion ink of a finely divided metal, neither the linear electrode nor the planar electrode including an electrical connection through the upper sheet; providing a second raw sheet of the fine high purity alumina dielectric material with a hole extending therethrough; filling the hole with said dispersion ink to form a conductor; laying the first sheet upon the second sheet so that the planar electrode on the lower surface of the first sheet directly contacts the second sheet; and sintering the layered sheets subsequent to said filling step.
 2. A method for making an electric field device according to claim 1 further comprising forming a disk-shaped conductor on each of the upper and lower surfaces of the second raw sheet, said circular conductors being coupled to the conductor filling the hole.
 3. A method of making a high voltage electric field device used for the formation of a corona discharge comprising:providing an upper raw sheet of a fine high purity alumina ceramic dielectric material, the sheet including an upper side and an opposite lower side, the lower side having a central area and a peripheral area surrounding the central area; forming a linear electrode on the upper surface of the upper sheet by applying a dispersion ink of finely divided tungsten; forming a planar electrode on only the central area of the lower surface of the upper sheet by applying a dispersion of ink of finely divided tungsten, neither of the electrodes including electrical connections extending through the upper sheet; providing a lower raw sheet of the fine high purity alumina ceramic dielectric material; forming a plurality of unrestricted holes extending through both of said sheets; laying the lower sheet over the lower surface of the upper sheet with the lower sheet overlying the central and peripheral areas; press-bonding the upper and lower sheets together; and sintering the press-bonded upper and lower sheets.
 4. A method of making an electric field device according to claim 3 wherein both of said forming steps include printing with said dispersion ink.
 5. A method of making an electric field device as defined in claim 3 wherein said second forming step includes leaving an unprinted margin portion surrounding each of the unrestricted holes.
 6. A method of making a high voltage electric field device used for the formation of a corona discharge comprising:providing an upper raw sheet of a fine high purity alumina ceramic dielectric material, the sheet including an upper side and an opposite lower side, the lower side having a central area and a peripheral area surrounding the central area; forming a linear electrode on the upper surface of the upper sheet by applying a dispersion ink of finely divided tungsten; forming a planar electrode on only the central area of the lower surface of the upper sheet by applying a dispersion of ink of finely divided tungsten, neither of the electrodes including electrical connections extending through the upper sheet; providing a lower raw sheet of the fine high purity alumina ceramic dielectric material; laying the lower sheet over the lower surface of the upper sheet with the lower sheet overlying the central and peripheral areas; press-bonding the upper and lower sheets together; shaping both of said sheets to form a hollow cylinder; and sintering the press-bonded upper and lower sheets. 